The invention relates to an actuator configuration, in particular, for actuating an injection valve of an internal combustion engine.
Prior art internal combustion engines include injection systems in which the injection valves are activated by actuators electrically actuated by an output stage with a power transistor, the output stage being embodied separately from the actuator and being connected thereto through a cable.
Prior art actuators also have an output stage integrated into the actuator with the cable connection between the actuator and output stage dispensed with so that the actuator can be connected directly to the engine controller through a control line. In the engine controller, all that is then necessary, instead of the output stage, is a line driver, which is capable of detecting faults on the control line between the engine controller and the actuator. In the event of a disconnection of or a short circuit in the control line, the engine controller can, therefore, immediately initiate suitable measures. However, faults diagnostics of the output stage integrated into the actuator are not possible by the line driver in the engine controller.
Therefore, prior art intelligent actuators have diagnostic capabilities in order to monitor the operating state of the actuator and the output stage. Thus, for example, short-circuits to ground or battery voltage, line breaks in the actuator, failure of the output stage, or a loss of the supply voltage can be detected during the operation of such an intelligent actuator configuration. For detection purposes, a diagnostic circuit is integrated into the actuator and it measures the output current and voltage and compares the measured values with predefined reference values. When a fault is detected, the diagnostic circuit then transmits an appropriate signal to the engine controller on a separate line.
A disadvantage with such intelligent actuators is the fact that a separate line is necessary to signal the operating state back to the engine controller.
It is accordingly an object of the invention to provide an actuator configuration, in particular, for actuating an injection valve of an internal combustion engine that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that has an intelligent actuator configuration with an integrated output stage and diagnostic capabilities with no need for a separate line for signaling the operating state back to the engine controller.
With the foregoing and other objects in view, there is provided, in accordance with the invention, an actuator configuration, including an electrically activated actuator, a power switch connected to the actuator for activating the actuator, at least one switch, a control input for receiving a control signal from an external control unit through a control line, the control signal actuating the power switch, the control input connected to the power switch and the at least one switch for influencing electrical input characteristics of the actuator configuration, and a diagnostic circuit for sensing at least one operating state of the actuator configuration, the diagnostic circuit having a circuit input connected to at least to one of the group consisting of the actuator and the power switch and a circuit output connected to the at least one switch for influencing the input characteristics as a function of the at least one operating state and, as a result, permitting remote diagnostics by the external control unit through the control line. In particular, the actuator configuration actuates an injection valve of an internal combustion engine
The invention includes the general technical teaching of transmitting the operating stage of the intelligent actuator configuration to the engine controller through the control line that is present in any case so that a separate line for signaling back the operating state can be dispensed with.
The signaling back of the operating state by the intelligent actuator configuration to the engine controller is preferably carried out by influencing the input characteristics of the actuator configuration as a function of the current operating state. The term xe2x80x9cinput characteristicsxe2x80x9d is to be understood here, and below, in a general sense and includes all status variables at the control input of the intelligent actuator configuration that can be registered by the engine controller through the control line and, thus, permit signaling back by the intelligent actuator configuration to the engine controller.
In one variant of the invention, the status-dependent change in the input characteristics takes place by virtue of the fact that the input impedance of the control input 4 is changed. For such a purpose, the control line in the intelligent actuator configuration can be connected to ground, for example, through resistors and switching elements. The engine controller can then measure the line resistance on the control line and determine the operating state of the actuator configuration therefrom. Instead of resistors, the control line can also be connected to ground or to battery voltage through other components, for example, capacitors or inductors. The input impedance of the actuator configuration can also be changed in a plurality of stages in order to be able to signal a plurality of operating states to the engine controller. Such a configuration can be carried out, for example, by connecting the control line in the actuator configuration to ground through a plurality of resistors and corresponding switching elements, the individual resistors having different resistance values.
In accordance with another feature of the invention, there is provided a second resistor, and there are at least two switches, a second of the switches connecting the control input to ground through the second resistor. Preferably, the second resistor has a resistance smaller than the given resistance. In particular, the second resistor has a resistance substantially smaller than the given resistance.
In accordance with a further feature of the invention, there is provided a third resistor, and there are three switches, a third of the switches connecting the control input to a supply voltage through the third resistor.
In addition to the passive change in the input characteristics that is described above, it is, however, also possible to influence the input characteristics actively. The influence can be carried out, for example, by connecting the control line in the actuator configuration to the battery voltage through a switching element. The engine controller then detects the operating state of the intelligent actuator configuration from the voltage on the control line. The signaling back of the operating state from the actuator configuration to the engine controller can also be carried out by transmitting data bi-directionally on the control line if the requirement of real-time operation of the actuator configuration permits it. In a digital transmission of data, such transmission is possible, for example, within the framework of a full duplex or half-duplex mode. On the other hand, given an analog transmission of data between the actuator configuration and the engine controller, the signaling-back signal can be transmitted in a different frequency range from that of the control signal generated by the engine controller. The separation of the control signal from the signaling-back signal can be effected easily by appropriately tuned bandpass filters.
The methods of influencing the input characteristics described above have in common the fact that the control input in the intelligent actuator configuration is connected to a controllable switching element. The actuation of the input characteristics is carried out by a diagnostic circuit that is connected at the output end to the switching element at the control input in order to influence the input characteristics of the actuator configuration as a function of the operating state.
In accordance with an added feature of the invention, there are provided a plurality of switches, and the diagnostic circuit has a logic circuit with digital inputs and digital outputs and a comparator unit with analog inputs and digital outputs. The comparator unit is connected to the logic circuit for driving the logic circuit. The analog inputs are connected to the actuator and to the power switch for sensing the at least one operating state, and the digital outputs of the logic circuit are respectively connected to one of the switches for influencing the input characteristics at the control input.
In accordance with an additional feature of the invention, the digital outputs of the comparator unit are connected to the digital inputs of the logic circuit.
In the preferred embodiment of the invention, the diagnostic circuit is composed of a comparator unit and a logic circuit connected downstream. The comparator unit is connected at the input end to the output stage and/or to the actuator itself and measures current and/or voltage at these measuring points. The measured values in the comparator unit are then compared with predefined reference values to analyze the operating state of the actuator configuration. At the output end, the comparator unit then actuates the logic circuit, which activates a plurality of switching elements at the control input of the actuator configuration as a function of the operating state and, as a result, determines the input impedance at the control input.
With the objects of the invention in view, there is also provided a method for actuating an actuator configuration, in particular, an injection valve of an internal combustion engine, including the steps of providing an actuator configuration having a control input, an electrically activated actuator, and a power switch for activating the actuator, producing a control signal with an external control unit and transmitting the control signal through a control line to the control input, actuating the power switch with the control signal through the control input, sensing an operating state of the actuator configuration with a diagnostic circuit having an input connected at least to one of the group consisting of the actuator and the power switch, influencing electrical input characteristics of the actuator configuration by connecting the control input to at least one switch, and influencing the input characteristics as a function of an operating state of the actuator configuration by connecting an output of the diagnostic circuit to the at least one switch and, as a result, enabling remote diagnostics by the external control unit through the control line.
The intelligent actuator configuration and method according to the invention is suitable in a particularly advantageous way for use in an injection system of an internal combustion engine, in particular, in a common-rail injection system. However, the invention is not restricted to this field of application. Instead, the inventive principle of an intelligent actuator with a remote diagnostic facility through the control line that is present in any case can also be used in other technical fields.
Other features that are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an actuator configuration, in particular, for actuating an injection valve of an internal combustion engine, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.